JP5839573B2 - Heat curable conductive paste composition - Google Patents

Description

  The present invention relates to a thermosetting conductive paste composition, and more specifically, to form an electrode or electrical wiring having excellent conductivity by heating and curing a coating film formed by printing on a substrate. The present invention relates to a heat-curable conductive paste composition that can be used.

  2. Description of the Related Art Conventionally, a method using a conductive paste composition is widely known as one of methods for forming an electrode or electrical wiring (wiring) on a substrate such as a film, a substrate, or an electronic component. In this method, when the conductor pattern is formed at a relatively low temperature, a thermosetting type containing conductive metal powder (conductive particles) and a thermosetting resin is used. Then, this heat curable conductive paste composition is applied or printed on the substrate with a predetermined conductor pattern, and then heating is performed to dry and cure the conductor pattern on the substrate, thereby Conductor pattern electrodes, wiring, and the like are formed on the substrate.

  Here, with higher performance of electronic devices and electronic components in recent years, higher electrical conductivity is required for the electrodes, wirings, etc., and this requirement is becoming stricter year by year. Therefore, various improvements have been made to the conductive paste composition for forming the electrodes, wirings and the like so as to realize high conductivity.

  In order to achieve the high conductivity mentioned here, it is well known to reduce the specific resistance (also referred to as volume resistance or bulk resistance) of electrodes and wirings. It is also important that the contact resistance with the conductor is small. For example, in a solar cell having an amorphous silicon layer, reducing the contact resistance between the current collecting electrode and the transparent conductive film greatly affects the conversion efficiency. Therefore, when the current collecting electrode is formed of a conductive paste composition, it is required not only to reduce the specific resistance but also to reduce the contact resistance.

  Examples of a method for reducing not only the specific resistance but also the contact resistance of an electrode or wiring formed of a conductive paste composition include the method disclosed in Patent Document 1 or 2.

  Patent Document 1 discloses a photovoltaic device in which a collecting electrode (“collecting electrode” in Patent Document 1) is formed of a conductive paste composition containing a granular conductive filler and a flaky conductive filler. In the conductive paste composition, the content of the granular conductive filler with respect to the entire conductive filler is 40% by weight or more. According to Patent Document 1, it is said that the contact resistance of the current collecting electrode can be reduced in addition to the reduction in resistance and thinning of the conductive paste composition having such a configuration.

  Patent Document 2 discloses a photoelectric conversion device in which a metal thin film having a thickness of 5 nm or more is interposed between an oxide transparent conductive film and a collector electrode (“collector electrode” in Patent Document 2). Yes. In the embodiment, a conductive paste composition for forming a collecting electrode is disclosed in which 0-50 mass% urethane resin is added to an epoxy resin and silver fine powder is kneaded, and a metal thin film is sputtered. An Ag thin film formed by the method is disclosed. According to Patent Document 2, it is said that the contact resistance between the collector electrode and the transparent conductive film can be reduced by interposing such a metal thin film.

  By the way, in the field of solar cells, a method using a plurality of types of epoxy resins is known in order to improve adhesion in addition to thinning and lowering the resistance of electrodes and wirings formed from a conductive paste composition. It has been. Specifically, Patent Document 3 discloses a conductive ink composition containing two types of epoxy resin compositions A and B as a thermosetting resin composition in a predetermined content ratio.

  One epoxy resin composition A is solid at room temperature and has a melt viscosity at 150 ° C. of 0.5 Pa · s or less, and the other epoxy resin composition B is liquid at room temperature, The viscosity is 10 Pa · s or less. And when the total amount of an epoxy resin composition is 100 mass%, the content rate of the epoxy resin composition A and the epoxy resin composition B is 50-85: 15-50 by mass ratio, and the epoxy resin composition A and The total amount of the epoxy resin composition combined with the epoxy resin composition B and the content ratio of the conductive particles are 2 to 15:75 to 95 by mass ratio.

  According to Patent Document 3, by using the conductive ink composition having such a configuration, the electrode width is further reduced and the resistance is reduced in the collector electrode of the solar cell (“collector electrode” in Patent Document 3). In addition, it is said that a highly reliable electrode having excellent adhesion and excellent heat resistance can be formed even in a narrow and narrow adhesion area.

JP 2002-76398 A Japanese Patent No. 4229858 JP 2010-83953 A

  In patent document 1, specific resistance is made low and contact resistance is made small by specifying content of the granular conductive filler contained in the whole conductive filler (conductive powder).

  Patent Document 2 discloses that the conductive powder is not studied, but the disclosed photoelectric conversion device has an additional configuration of a metal thin film. Therefore, in addition to the general process of forming the current collecting electrode using the conductive paste composition, a process of forming a metal thin film by a sputtering method or the like is required, so that an increase in manufacturing cost is expected. Further, Patent Document 2 discloses a combination of an epoxy resin and a urethane resin as thermosetting components, but does not disclose any more specific configuration of these resin components.

  On the other hand, Patent Document 3 does not disclose reducing contact resistance as a problem, and therefore, no mention or suggestion is made regarding contact resistance in the embodiment or the like. It is disclosed that spherical conductive particles having an average particle diameter of 0.1 to 3 μm and flaky conductive particles having an average flake diameter of 0.1 μm or more and less than 3 μm are used as the conductive powder. ing. However, the flaky conductive particles tend to be more expensive as the diameter becomes smaller. For example, the flaky silver powder having an average flake diameter of 0.5 μm used in the Examples is compared with the silver powder having substantially the same diameter. Expensive. Therefore, it is difficult to supply the conductive paste composition at low cost by the method disclosed in Patent Document 3.

  The present invention has been made to solve such problems, and is a thermosetting type capable of reducing specific resistance of formed electrodes, wirings, and the like and reducing contact resistance with other conductors. An object is to provide a conductive paste composition at low cost.

  In order to solve the above-mentioned problems, the heat-curable conductive paste composition according to the present invention contains a conductive powder, a thermosetting component, a curing agent, and a solvent as the conductive powder. , Flaky powder and spherical powder are used, and the thermosetting component is component A: epoxy equivalent is 160 or more and 400 or less, and viscosity at 25 ° C. is 3,000 mPa · s or more and 55,000 mPa · s or less. An epoxy resin having a cyclic structure, and a component B: an epoxy equivalent having an epoxy equivalent of 140 or more and 300 or less and a viscosity at 25 ° C. of 30 mPa · s or more and less than 3,000 mPa · s, and a C component : Consists of three components with a blocked polyisocyanate compound, and these A to C components are in a mass ratio, and the total amount of component A and component B and the amount of component C are 30. 70 to 90:10, and the amount of the B component and the total amount of the A and C components are blended so as to be within the range of 10:90 to 70:30. The ratio of the conductive powder is in the range of 90 to 98% by mass, and the viscosity at 25 ° C. is in the range of 200 to 500 Pa · s.

  In the heat curable conductive paste composition, the component A is selected from the group consisting of bisphenol A type, bisphenol E type, bisphenol F type, phenol novolac type, chelate modified type, urethane modified type, and rubber modified type. At least one epoxy resin may be used.

  In the heat curable conductive paste composition, the component B is at least selected from the group consisting of cyclohexanedimethanol type, dicyclopentadienedimethanol type, propylene oxide-added bisphenol A type, and chelate-modified type. One kind of epoxy resin may be used.

  In the heat curable conductive paste composition, a blocked polyisocyanate compound containing a polymethylene polyphenyl polyisocyanate having three or more nuclei may be used as the C component.

  Moreover, in the said thermosetting conductive paste composition, it is preferable that the said flaky powder and spherical powder are in the range of 20: 80-80: 20 by mass ratio.

  In the heat curable conductive paste composition, the conductive powder is selected from the group consisting of silver powder, copper powder, silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, and silver-coated glass powder. At least one of the above may be used.

  In the heat curable conductive paste composition, the conductive powder may have a sodium ion content of less than 200 ppm.

Further, in the above heat-curable conductive paste composition, as the curing agent, acid anhydride, imidazole, a tertiary amine emissions or, it may be a Lewis acid or a compound used include boron fluoride .

  Moreover, in the said thermosetting conductive paste composition, it may be used for the use which forms an electrode or an electrical wiring on the said base material by heat-hardening the conductor pattern printed on the base material. At this time, examples of the electrode include a collecting electrode of a solar cell.

  In the present invention, it is possible to provide a thermosetting conductive paste composition that can reduce the specific resistance of formed electrodes, wirings, and the like and reduce the contact resistance with other conductors at low cost. , Has the effect.

It is a top view which shows the shape of the conductor pattern for evaluating the characteristic (contact resistance) of the thermosetting conductive paste composition which concerns on this invention. It is a top view which shows the shape of the conductor pattern for evaluating the characteristic (specific resistance) of the thermosetting conductive paste composition which concerns on this invention. It is a top view which shows the shape of the conductor pattern for evaluating the characteristic (conductor pattern formation) of the thermosetting conductive paste composition which concerns on this invention.

  The thermosetting conductive paste composition according to the present invention contains, as components, a conductive powder, a thermosetting component, a curing agent, and a solvent, of which the thermosetting component is: Component A: epoxy equivalent having an epoxy equivalent of 160 to 400 and a viscosity at 25 ° C. of 3,000 mPa · s to 55,000 mPa · s and B component: epoxy equivalent of 140 to 300 It is composed of three components: an epoxy resin having a cyclic structure having a viscosity at 25 ° C. of 30 mPa · s or more and less than 3,000 mPa · s, and a component C: blocked polyisocyanate compound. These A to C components are in a mass ratio of A component + B component and C component in the range of 30:70 to 90:10, and B component and A component + C component are in the range of 10:90 to 70:30. It is mix | blended so that it may become in the range. In the heat curable conductive paste composition, the ratio of the conductive powder in the solid content is in the range of 90 to 98% by mass, and the viscosity at 25 ° C. is 200 to 500 Pa · s. It is within the range.

  In the following description, the thermosetting conductive paste composition according to the present invention is simply abbreviated as a conductive paste composition. In addition, solid content here is the sum total of electroconductive powder and a thermosetting component.

  Next, the preferred embodiments of the respective components of the conductive paste composition according to the present invention, the AC components used as thermosetting components, and the production and use of the conductive paste composition are as follows. Will be described in detail.

[Conductive powder]
As the conductive powder used in the conductive paste composition according to the present invention, flaky powder and spherical powder are used in combination from the viewpoint of realizing good conductivity.

  The flaky powder in the present invention may be a powder having a shape close to a flat plate or a thin rectangular parallelepiped when viewed as a whole, even if there is unevenness and deformation is seen partially. In addition, flake shape can be paraphrased as flake shape or scale shape. In addition, the spherical powder in the present invention may be a three-dimensional powder that is closer to a cube than a rectangular parallelepiped when viewed as a whole, even if there are irregularities and deformation is observed. Note that the spherical shape can be restated as granular.

  In the present invention, flaky powder and spherical powder are used in combination as the conductive powder. For example, when only the flaky powder is used, the contact area between the conductive powders can be increased, so that high conductivity can be expected. However, since a lubricant is used in the production process of the flaky powder, if only the flaky powder is used, the adhesiveness may be lowered.

  Further, since the flaky powder has a shape having a two-dimensional spread, when only the flaky powder is used, the thickness of the cured product (electrode, wiring, etc.) may be increased due to the shape. It tends to be difficult. Therefore, for example, when a wiring is formed, the resistance value of the wiring may not be as low as expected. In addition, the flaky powder has a relatively higher manufacturing cost than the spherical powder due to its manufacturing process (described later). Therefore, when only the flaky powder is used, cost reduction may be hindered. .

  Or when only spherical powder is used, since the contact area of electrically conductive powder becomes small compared with flaky powder, there is a possibility that specific resistance cannot be lowered sufficiently. Therefore, in the present invention, the flaky powder and the spherical powder are used in combination from the viewpoint of further improving the physical properties of the obtained conductive paste composition and reducing the cost.

  The blending ratio of the flaky powder and the spherical powder is not particularly limited, but when the total of both is 100 parts by mass, the flaky powder is in the range of 20 to 80 parts by mass, and the spherical powder is 80 to 20 parts by mass. The flaky powder is preferably in the range of 40 to 60 parts by mass, and the spherical powder is more preferably in the range of 60 to 40 parts by mass. In other words, the flaky powder and the spherical powder are preferably blended so as to have a mass ratio in the range of 20:80 to 80:20, and in the range of 40:60 to 60:40. It is more preferable that they are blended as described above.

  When the flaky powder or spherical powder exceeds 80 parts by mass or less than 20 parts by mass, there is a possibility that the effect of improving the conductivity due to the combined use of the two may not be obtained sufficiently, and the film and substrate There is also a possibility that excellent adhesiveness to a substrate such as an electronic component cannot be obtained.

  Moreover, the ratio (content) in solid content of electroconductive powder should just be in the range of 90-98 mass%, and it is preferable that it is in the range of 92-97 mass%, and 93-97 mass%. More preferably within the range. Solid content here is the sum total of electroconductive powder and a thermosetting component as above-mentioned.

  If the content of the conductive powder is less than 90% by mass, the contact density of the conductive powder becomes small, and the conductivity becomes insufficient due to poor contact between the conductive powders, which is not preferable. On the other hand, when the content of the conductive powder is more than 98% by mass, it is not preferable because the conductive powder may not be uniformly dispersed by the resin component. If the conductive powder cannot be uniformly dispersed in the conductive paste composition, problems such as a distorted conductor pattern or formation of a non-uniform conductor pattern occur.

Of the conductive powder in the present invention, a preferred configuration of the flaky powder will be specifically described. The average particle diameter D50 of the flaky powder is preferably in the range of 2 to 20 μm, the BET specific surface area is preferably in the range of 0.1 to ¹ m ² / g, and the tap density is 3 to 7 g / cm. It is preferable to be within the range of ³ , and the aspect ratio is preferably within the range of 5 to 15.

  More specifically, the average particle diameter D50 of the flaky powder is preferably in the range of 2 to 20 μm as described above, more preferably in the range of 2 to 12 μm, and in the range of 6 to 10 μm. Further preferred. If the average particle diameter D50 of the flaky powder is smaller than 2 μm, the contact resistance between the conductive powders tends to increase, and sufficient conductivity may not be obtained. On the other hand, if the average particle diameter D50 is larger than 20 μm, the contact resistance between the conductive powders becomes small. However, when a conductor pattern is printed using a mesh screen, the mesh screen is clogged or fine wiring is formed. It may be difficult.

The BET specific surface area of the flaky powder is preferably in the range of 0.1 to ¹ m ² / g as described above, but more preferably in the range of 0.2 to 0.8 m ² / g. More preferably, it is in the range of ^{2 to} 0.5 m ² / g. If the BET specific surface area of the flaky powder is smaller than 0.1 m ² / g, the flake thickness becomes too thick and the shape of the flaky powder becomes nearly spherical, so the contact area between the conductive powders tends to be small. Sufficient conductivity may be obtained. On the other hand, if the BET specific surface area exceeds 1 m ² / g, the contact area between the conductive powders becomes large, but the paste viscosity becomes high, so that high filling becomes difficult (that is, in the conductive paste composition). There is a tendency that it is difficult to improve the content of the conductive powder), so that sufficient conductivity may not be obtained.

The tap density of the flaky powder is preferably in the range of ^{3 to} 7 g / cm ³ as described above, more preferably in the range of ^{3 to} 6 g / cm ³ , and 3.5 to 5.5 g / cm. If it is in the range of ³ , it is more preferable. If the tap density of the flaky powder is less than 3 g / cm ³ , the flaky powder tends to be bulky and high filling tends to be difficult, so that sufficient conductivity may not be obtained. On the other hand, if the tap density exceeds 7 g / cm ³ , it is usually difficult to industrially produce the flaky powder.

  The aspect ratio of the flaky powder is preferably in the range of 5 to 15 as described above, more preferably in the range of 6 to 12, and further preferably in the range of 6 to 10. If the aspect ratio of the flaky powder is less than 5, flaking is insufficient and the contact area between the conductive powders tends to be small, and sufficient conductivity may not be obtained. On the other hand, if the aspect ratio exceeds 15, the contact area between the conductive powders becomes large, but it tends to be difficult to achieve high filling, so there is a possibility that sufficient conductivity cannot be obtained.

  The manufacturing method of the said flaky powder is not specifically limited, A well-known method can be used. Specifically, for example, a flaky powder can be produced by using a spherical powder (described later) produced by a known method as a base powder and subjecting the base powder to a known mechanical treatment. The physical properties such as the particle size and cohesion of the base powder are appropriately determined according to the purpose of use of the conductive paste composition (types of electrodes, wirings, etc., or types of electronic components or electronic devices equipped with these electrodes, wirings, etc.) You can choose.

Next, a preferable configuration of the spherical powder among the conductive powders in the present invention will be specifically described. The average particle diameter D50 of the spherical powder is preferably in the range of 0.1 to 10 μm, the BET specific surface area is preferably in the range of 0.5 to 1.7 m ² / g, and the tap density is 1. It is preferable that it is 5-5 g / cm < ³ >, and it is preferable that the aggregation degree D50 / DSEM exists in the range of 2-15.

  More specifically, the average particle diameter D50 of the spherical powder is preferably in the range of 0.1 to 10 μm as described above, more preferably in the range of 1 to 5 μm, and in the range of 1 to 3 μm. More preferred. If the average particle diameter D50 of the spherical powder is smaller than 0.1 μm, the conductive paste composition may become highly viscous and it may be difficult to make a paste. On the other hand, if the average particle diameter D50 is larger than 10 μm, as in the case of the flaky powder, when a conductor pattern is printed using a mesh screen, the mesh screen is clogged or it is difficult to form fine wiring. There is a risk of

The BET specific surface area of the spherical powder is preferably in the range of 0.5 to 1.7 m ² / g as described above, but more preferably in the range of 0.6 to 1.6 m ² / g, 0 More preferably, it is in the range of 1.9 to 1.6 m ² / g. If the BET specific surface area of the spherical powder is smaller than 0.5 m ² / g, the contact area between the conductive powders tends to be small, and sufficient conductivity may not be obtained. On the other hand, if the BET specific surface area exceeds 1.7 m ² / g, the contact area between the conductive powders becomes large, but the paste viscosity tends to be high and high filling becomes difficult, so that sufficient conductivity is obtained. May not be obtained.

Moreover, the tap density of the spherical powder is in the range of as 1.5 to 5 g / cm ³ of the preferably, more preferably be within the range of 2-5 g / cm ^3, a range of 3 to 4 g / cm ³ If it is in, it is more preferable. If the tap density of the spherical powder is less than 1.5 g / cm ³ , the conductive powder tends to be bulky and high filling tends to be difficult, so that sufficient conductivity may not be obtained. On the other hand, if the tap density exceeds 5 g / cm ³ , the dispersibility of the spherical powder becomes too good, and the resin component tends to wrap around between the conductive powders, so that the interfacial resistance between the conductive powders tends to increase. Therefore, sufficient conductivity may not be obtained.

  Further, as described above, the aggregation degree D50 / DSEM of the spherical powder is preferably in the range of 2 to 15, more preferably in the range of 3 to 11, and further preferably in the range of 3 to 7.5. . If the degree of aggregation D50 / DSEM is less than 2, the dispersibility of the spherical powder becomes too good, and the resin component tends to wrap around between the conductive powders, so the interface resistance between the conductive powders tends to increase. There is a risk that sufficient conductivity cannot be obtained. On the other hand, if the degree of aggregation D50 / DSEM is greater than 15, the conductive powder tends to be bulky and high filling tends to be difficult, so that sufficient conductivity may not be obtained.

  The method for producing the spherical powder is not particularly limited, and in the present embodiment, for example, a product produced by a wet reduction method can be suitably used, but other known methods such as an electrolytic method and an atomizing method can be used. A spherical powder produced by the method can also be used.

  As the conductive powder used in the present invention, any of the flaky powder and the spherical powder may be a powder containing a metal having a relatively low resistance. Specifically, the low-resistance metal is not particularly limited, but gold, silver, copper, and alloys thereof can be preferably used. The material composition of the specific powder (particles) is not particularly limited, but typically, silver powder, copper powder, silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, silver-coated glass powder, etc. Can be mentioned. Only one type of these material configurations may be used, or two or more types may be used in appropriate combination.

  Here, in this invention, it is preferable that the upper limit of the amount of alkali metal ions contained in electroconductive powder is defined. Specifically, both the amount of sodium ions and the amount of potassium ions contained in the conductive powder are preferably less than 200 ppm, more preferably less than 100 ppm, and even more preferably less than 10 ppm. In the present invention, it is preferable that at least the amount of sodium ions is less than 200 ppm. If the amount of these ions exceeds 200 ppm, problems are likely to occur in the electrical characteristics and reliability of an electronic component or electronic device in which electrodes and wirings are formed from the conductive paste composition. On the other hand, the lower the lower limit of these ions, the better.

[Thermosetting component]
The thermosetting component used in the conductive paste composition according to the present invention is two types of epoxy resins that are liquid at 25 ° C. and have a cyclic structure, and a blocked polyisocyanate compound. These two types of epoxy resins and blocked polyisocyanate compounds are used in combination at a predetermined mixing ratio.

  One of the two types of epoxy resins has a physical property of having an epoxy equivalent of 160 to 400 and a viscosity at 25 ° C. of 3,000 mPa · s to 55,000 mPa · s, and the other is an epoxy. An equivalent is 140 or more and 300 or less, and it has the physical property that the viscosity in 25 degreeC is 30 mPa * s or more and less than 3,000 mPa * s. For convenience of explanation, the former epoxy resin is referred to as component A, and the latter epoxy resin is referred to as component B. Moreover, since the blocked polyisocyanate compound is a thermosetting component like the A component and the B component, it is referred to as a C component for convenience of explanation.

  The epoxy equivalent can be calculated according to JIS-K-7236. The unit of epoxy equivalent is [g / eq]. In the present embodiment, the viscosity of the epoxy resin is measured by a TV-33H viscometer manufactured by Toki Sangyo Co., Ltd. The measurement temperature is 25 ° C.

  Any of the two types of epoxy resins (component A and component B) may be those having the above-mentioned physical properties, and the specific structure thereof is not particularly limited, but both of them have two or more oxirane rings in one molecule. A polyvalent epoxy resin having (epoxy group) is preferred.

  Moreover, although both said 2 types of epoxy resins contain the cyclic structure, this cyclic structure is not specifically limited. Preferred cyclic structures include benzene ring, naphthalene ring, anthracene ring, cyclohexane ring, norbornyl ring, adamantyl ring, dicyclopentane ring, tricyclodecane ring, tetracyclododecane ring, bornene ring, decahydronaphthalene ring, polyhydroanthracene. A ring etc. can be illustrated, More preferably, a benzene ring, a naphthalene ring, a cyclohexane ring, a dicyclopentane ring etc. are mentioned.

  As described above, the physical properties of one component A of the two types of epoxy resins are that the epoxy equivalent is 160 to 400 and the viscosity at 25 ° C. is 3,000 mPa · s to 55,000 mPa · s. More preferably, the epoxy equivalent is 160 or more and 320 or less, and the viscosity at 25 ° C. is 3,000 mPa · s or more and 55,000 mPa · s or less. Specific types of epoxy resins having such physical properties and including a cyclic structure are not particularly limited. For example, bisphenol A type, bisphenol E type, bisphenol F type, phenol novolac type, chelate modified type, urethane modified type, Another example is a rubber-modified epoxy resin. These epoxy resins may use only 1 type as A component, and may use it in combination of 2 or more types as appropriate.

  Moreover, as for the physical property of the other B component among the two types of epoxy resins, as described above, the epoxy equivalent is 140 or more and 300 or less, and the viscosity at 25 ° C. is 30 mPa · s or more and less than 3,000 mPa · s. More preferably, the epoxy equivalent is 140 or more and 190 or less, and the viscosity at 25 ° C. is 30 mPa · s or more and 1,000 mPa · s or less. Specific types of epoxy resins having such physical properties and containing a cyclic structure are not particularly limited. For example, cyclohexane dimethanol type, dicyclopentadiene dimethanol type, propylene oxide-added bisphenol A type, chelate modified type epoxy Resins can be mentioned. These epoxy resins may use only 1 type as B component, and may use it in combination of 2 or more types as appropriate.

  As the C component used as the thermosetting component in the present invention, that is, the blocked polyisocyanate compound, a compound known in the field of the conductive paste composition can be suitably used.

  Specifically, as the polyisocyanate compound in the present invention, for example, aroma such as tolylene diisocyanate, diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, tolidine diisosonate, xylylene diisosonate, naphthalene diisosonate. An aliphatic polyisocyanate such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, dicyclohexylmethane diisocyanate, octamethylene diisocyanate, trimethylhexamethylene diisocyanate; These polyisocyanate compounds may be used alone or in combination of two or more. Of these polyisocyanate compounds, polymethylene polyphenyl polyisocyanates having three or more nuclei are more preferably used.

  In the present embodiment, a terminal isocyanate group-containing compound synthesized by reacting a known polyisocyanate and a known polyol by a known method can also be suitably used as the polyisocyanate compound in the present invention. The polyol used in this case is not particularly limited, and general polyether polyols, polyester polyols, polycarbonate polyols and the like can be suitably used.

  The blocked polyisocyanate compound of component C in the present invention is obtained by blocking the polyisocyanate compound described above, but the blocking agent for the polyisocyanate compound is not particularly limited, and imidazoles, phenols, oximes, etc. Can be suitably used.

  In the conductive paste composition according to the present invention, the A to C components used as the thermosetting component have a mass ratio of the total amount of the A component and the B component (A component + C component) and the C component within a predetermined range. And it mix | blends so that mass ratio of B component, and the total amount (A component + C component) of A component and C component may be in a predetermined range.

  Specifically, the A component + C component and the C component may be blended in a mass ratio within a range of 30:70 to 90:10, and blended within a range of 50:50 to 80:20. It is more preferable. Moreover, B component and A component + C component should just be mix | blended in the range of 10: 90-70: 30 by mass ratio, and may be mix | blended in the range of 25: 75-40: 60. preferable.

  When the total of the A to C components is 100 parts by mass, if the A component + B component is less than 30 parts by mass, that is, if the C component exceeds 70 parts by mass, the resulting cured product (electrode, wiring, etc.) Since strength and adhesiveness are lowered, it is not preferable. On the other hand, if the A component + B component exceeds 90 parts by mass, that is, if the C component is less than 10 parts by mass, the effect of promoting the contact between the conductive powders due to curing shrinkage of the C component is reduced, and the conductivity is lowered. This is not preferable. Further, if the B component is less than 10 parts by mass, that is, if the A component + C component exceeds 90 parts by mass, the contact resistance between the obtained electrode, wiring, etc. and other conductors is not preferable. On the other hand, if the B component exceeds 70 parts by mass, that is, if the A component + C component is less than 30 parts by mass, the strength and adhesiveness of the resulting cured film are deteriorated.

  In the conductive paste composition according to the present invention, as described above, a predetermined content ratio of the A component epoxy resin, the B component epoxy resin, and the C component blocked polyisocyanate compound as the thermosetting component. Used in. Among these components, the epoxy resin of component A is the component that becomes the base of the thermosetting component, whereas the epoxy resin of component B improves the wettability with respect to other conductors and improves the contact resistance. The blocked polyisocyanate compound of component C is a component that reduces the specific resistance.

  Among these, a good specific resistance can be realized by a combination of a predetermined ratio of the A component and the C component, but according to the C component, the contact resistance can be improved. Moreover, the B component is used in a predetermined ratio as the thermosetting component, and this B component can not only improve the contact resistance as described above but also improve the specific resistance. Therefore, by including the components A to C as the thermosetting component, the specific resistance and contact resistance can be further improved by the synergistic action of each component.

[Curing agent]
The curing agent used in the conductive paste composition according to the present invention is not particularly limited as long as it cures the epoxy resin of component A and component B. Various compounds known in the field of conductive paste compositions are used. Can be mentioned.

  Specifically, for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride Acid anhydrides such as acids; imidazole, 2-methylimidazole, 2-ethyl-4methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4methyl Imidazoles such as imidazole, 1-cyanoethyl-2-methylimidazole, 1-aminoethyl-2-methylimidazole, 1-methylimidazole, 2-ethylimidazole; dimethyloctylamine, dimethyldecylamine, dimethyllaurylamine, dimethyl Listylamine, dimethylpalmitylamine, dimethylstearylamine, dimethylbehenylamine, dilaurylmonoethylamine, methyldideylamine, methyldioleylamine, triallylamine, triisopropanolamine, triethylamine, 3- (dibutylamino) propylamine, tri-n -Tertiary amines such as octylamine, 2,4,6-trisdimethylaminomethylphenol, triethanolamine, methyldiethanolamine, diazabicycloundecene; boron trifluoride ethyl ether, boron trifluoride phenol, three Contains boron fluoride such as boron fluoride piperidine, boron trifluoride, boron trifluoride monoethylamine, boron trifluoride triethanolamine, boron trifluoride monoethanolamine Isic acid or a compound thereof; such as Amicure series PN-23 or MY-24 commercially available from Ajinomoto Fine Techno Co., Ltd., Fujicure series FXR-1020 or FXR-1030 commercially available from Fuji Kasei Kogyo Co., Ltd. Amine adducts; dicyandiamide; and the like. These compounds may be used alone or in combination of two or more.

  Although the addition amount of a hardening | curing agent is not specifically limited, In this Embodiment, when the total amount of 2 types of epoxy resins (A component + B component) is 100 mass parts, it is 3 to 100 mass parts of epoxy resin total amount. It is preferably within the range of 30 parts by mass, more preferably within the range of 3 to 15 parts by mass, and even more preferably within the range of 3 to 10 parts by mass. If the addition amount of the curing agent is less than 3 parts by mass, curing of the epoxy resin may be insufficient, and good conductivity may not be obtained in the cured product (electrode, wiring, etc.). On the other hand, if it exceeds 30 parts by mass, the paste viscosity may be increased, and it is not preferable in terms of cost.

[Solvent and paste viscosity]
The solvent used for the conductive paste composition according to the present invention is not particularly limited, and various solvents known in the field of the conductive paste composition can be suitably used.

  Specifically, for example, glycol ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether Acetate esters of these glycol ethers; DBE, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, etc. Esters; ketones such as cyclohexanone and isophorone; monoterpene alcohols such as terpineol and hydrogenated terpineol; Acetate of Luo monoterpene alcohols; .gamma.-butyrolactone; limonene; and the like. These solvents may be used alone or in combination of two or more.

  The conductive paste composition according to the present invention is particularly suitable for use in forming a conductor pattern by screen printing. Therefore, from the viewpoint of suppressing drying of the screen printing plate, it is preferable that more than half of the solvent contained in the conductive paste composition is a high boiling point solvent having a boiling point of 200 ° C. or higher. Although it does not specifically limit as such a high boiling point solvent, Specifically, for example, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Turpineol and the like can be preferably used. Note that only one kind of these high-boiling solvents may be used, or two or more kinds may be used in appropriate combination.

  Here, the paste viscosity of the conductive paste composition according to the present invention may be a viscosity that can be appropriately printed or applied on the substrate, and in particular, the paste viscosity at 25 ° C. is in the range of 200 to 500 Pa · s. It is preferable that it is in the range of 250 to 450 Pa · s. By setting the paste viscosity of the conductive paste composition in such a predetermined range, it is possible to improve the shape retention after the conductor pattern is formed by printing. In the case of wiring, it is possible to suppress wiring dripping or wiring bleeding. Therefore, it becomes possible to form a high-definition conductor pattern. For example, when the conductive paste composition is used for forming a collecting electrode of a solar cell, a reduction in the light receiving area of the solar cell is suppressed. be able to.

  Note that the viscometer for measuring the paste viscosity and its conditions are not particularly limited, but in this embodiment, as used in the examples and comparative examples described later, a Brookfield DV-III viscometer is used, and 1 rpm The paste viscosity (η1 rpm) is measured under measurement conditions during rotation. Here, in Examples and Comparative Examples, which will be described later, the paste viscosity was also measured when the measurement conditions were 5 rpm, and the TI value (η1 rpm / η5 rpm) obtained by dividing the paste viscosity at 1 rpm by the paste viscosity at 5 rpm. ) Is also calculated, and these comprehensively evaluate the paste viscosity. The paste viscosity at the time of 5 rpm rotation should just be in the range of 70-140 Pa * s, and the TI value should just be in the range of 2.0-5.0.

[Production and Use of Conductive Paste Composition]
The manufacturing method of the electrically conductive paste composition which concerns on this invention is not specifically limited, A well-known method can be used suitably in the field | area of the electrically conductive paste composition. As a typical example, there is a method in which the above-described components are blended at a predetermined blending ratio (mass basis) and formed into a paste using a known kneading apparatus. Examples of the kneading apparatus include a three roll mill.

  In addition, in the electrically conductive paste composition which concerns on this invention, it is well-known in the field | area of the electrically conductive paste composition other than each component mentioned above (electrically conductive powder, a thermosetting component, a hardening | curing agent, and a solvent) as needed. These various additives may be contained. Although it does not specifically limit as the said additive, Specifically, a dispersing agent, antioxidant, a ultraviolet absorber, a silane coupling agent, an antifoamer, a viscosity modifier etc. can be mentioned, for example. These additives can be added as long as the effects of the present invention are not hindered.

  The conductive paste composition according to the present invention includes the above components, and the components A to C are blended within a predetermined range as thermosetting components, and the content of the conductive powder in the solid content is suitable. Therefore, it can be widely used to form high-definition electrodes and wirings. Specifically, for example, a collector electrode of a solar battery cell; an external electrode of a chip-type electronic component; an RFID (Radio Frequency IDentification), an electromagnetic wave shield, a vibrator adhesive, a membrane switch, or a component used for electroluminescence It can be suitably used for applications such as electrodes or wirings. Among these applications, one of particularly preferable applications is a collecting electrode of a solar battery cell.

  When the conductive paste composition according to the present invention is used for forming a collecting electrode of a solar cell, the collecting electrode can be formed with higher definition, so that the reduction of the light receiving area can be suppressed. it can. And since it becomes possible to provide the electrically conductive paste composition itself at low cost, it becomes possible to improve the conversion efficiency of a solar cell at low cost.

  Furthermore, the electrode, wiring, etc. formed using the conductive paste composition according to the present invention can exhibit good solder wettability. Therefore, for example, it is possible to satisfactorily solder a tab ribbon used in a solar battery to a solar battery cell constituting the solar battery. This improvement in solder wettability is realized by blending the three components A to C as thermosetting components at the predetermined ratio. That is, it is possible to improve not only specific resistance and contact resistance but also solder wettability by further adding C component to the combination of A component and B component.

  Specifically, the solar battery is modularized by electrically connecting a plurality of solar battery cells in series with tab wires. As this tab wire, generally, a tab ribbon obtained by performing solder plating on a copper ribbon is used. Here, the current collecting electrode is generally composed of a finger electrode formed in a comb-teeth shape on the surface of a silicon wafer which is a main body of the solar battery cell, and a bus bar electrode connected to the finger electrode. Is connected to the bus bar electrode. If this bus bar electrode is formed of the conductive paste composition according to the present invention, the bonding property of the tab ribbon to the solar battery cell can be further improved.

  In addition, the electrodes, wirings, and the like formed using the conductive paste according to the present invention can not only exhibit good solder wettability but also have good contact with other conductors. Therefore, for example, it is possible to improve the contact between the collecting electrode of the solar cell and the transparent conductive film.

  When a conductive pattern to be a collecting electrode is formed with the conductive paste composition according to the present invention, the conductive paste composition has good wettability with respect to the transparent conductive film. The affinity with the conductive film can be improved. As a result, the contact between the conductive powder contained in the current collecting electrode and the transparent conductive film is improved, and the contact resistance can be reduced.

In addition, the material of a transparent conductive film is not specifically limited, A well-known material can be used suitably in the field | area of a solar cell. Specifically, for example, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), FTO (Fluorine doped Tin Oxide), ZnO (Zinc Oxide), AZO (Aluminum Doped Zinc Oxide), GZO (Gallium doped Zinc Oxide). , SnO ₂ (tin (IV) oxide) and the like.

  Here, the collector electrode formed of the conductive paste composition is opaque because it contains conductive powder and the like. Therefore, as the area of the collecting electrode on the surface of the solar battery cell increases, the light receiving area decreases and the power generation efficiency also decreases. On the other hand, since the conductive paste composition according to the present invention contains each of the above components and the paste viscosity is adjusted within a suitable range, the current collecting electrode can be formed with high definition. it can. Therefore, a reduction in the light receiving area can be effectively suppressed, and a reduction in power generation efficiency can be avoided.

  A specific method of using the conductive paste composition according to the present invention is not particularly limited, and a step of applying or printing the conductive paste composition on a base material in a predetermined conductor pattern (pattern forming step), and a base material Any method including a step of heat-curing the upper conductor pattern (heat-curing step) may be used. The conductor pattern (cured film) after curing becomes an electrode or wiring formed on the substrate.

  As said base material, the well-known film according to the electronic component or electronic device mentioned above, a board | substrate, and another base material can be mentioned. Specific materials, shapes, dimensions, and other conditions of these base materials are not particularly limited, and an appropriate material may be selected according to the type of electronic component or electronic device. In the pattern forming step, various known conductor pattern forming methods (printing method or coating method) can be used, but typically, screen printing using a mesh screen can be given.

  In the heat curing step, the heating method or the heating temperature is not particularly limited, but the heating temperature is preferably within a range of 100 to 250 ° C., which is a relatively low temperature. If the heating temperature is lower than 100 ° C, the conductive paste composition may be insufficiently cured. If the heating temperature is higher than 250 ° C, the thermosetting component may be decomposed or peeled off from the substrate.

  Thus, in this invention, since the epoxy resin of A component and the blocked polyisocyanate compound of C component are used together, a favorable specific resistance can be obtained. Further, since the B component is also used as the epoxy resin, the specific resistance can be improved, and the wettability with respect to the transparent conductive film is good, so that the contact resistance can be reduced. Moreover, since the ratio of the electroconductive powder in solid content is adjusted to 90-98 mass%, the filling property of the electroconductive powder in an electroconductive paste composition is improved, and the contact area of electroconductive powder is raised. The specific resistance can be lowered. Moreover, since the paste viscosity is adjusted within a suitable range, the wiring shape retention of the conductor pattern by printing is good, and when used for the collector electrode of a solar cell, the reduction of the light receiving area is suppressed. . In addition, if a flaky powder and a spherical powder are used in combination as the conductive powder, the cost of the conductive paste composition can be further reduced.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In addition, measurement and evaluation of physical properties and the like in the following examples and comparative examples were performed as follows.

[Evaluation method of conductive powder]
In the examples and comparative examples, flaky silver powder and spherical silver powder were used as the conductive powder. Among these, for the flaky silver powder, the average particle diameter D50, the maximum particle diameter Dmax, the aspect ratio, the BET specific surface area, the tap density, and the amount of sodium ions were evaluated. For the spherical silver powder, the average particle diameter D50, the maximum particle diameter Dmax, the average particle diameter DSEM, the degree of aggregation D50 / DSEM, the BET specific surface area, the tap density, and the amount of sodium ions were evaluated. Details of each evaluation will be described below.

(1) Evaluation of average particle diameter D50 and maximum particle diameter Dmax The average particle diameter D50 and the maximum particle diameter Dmax of the flaky silver powder and the spherical silver powder were evaluated by a laser diffraction method. A sample of 0.3 g of flaky silver powder or spherical silver powder was weighed into a 50 ml beaker, 30 ml of isopropyl alcohol was added, and then dispersed by treating for 5 minutes with an ultrasonic cleaner (USM-1 manufactured by ASONE Corporation). The average particle size D50 and the maximum particle size Dmax were measured and evaluated using a microtrack particle size distribution measuring device (Microtrack particle size distribution measuring device 9320-HRA X-100 manufactured by Nikkiso Co., Ltd.).

(2) Evaluation of average particle diameter DSEM Spherical silver powder was observed with a scanning electron microscope (SEM, JSM-5500 manufactured by JEOL Ltd.), and 100 particles were randomly selected from an image magnified 20,000 times. The particle size (major axis on the image) was measured. Then, the SEM particle size DSEM was calculated and evaluated by averaging the particle size of each particle.

(3) Evaluation of aspect ratio 10 particles were randomly selected from an image magnified 2,000 times by observing the flaky silver powder with a scanning electron microscope (JSM-5500 manufactured by JEOL Ltd.). Then, the particle size (diameter of the circumscribed circle) was measured, and the length of the long side was obtained by averaging the number. Similarly, ten particles were randomly selected from an image magnified 2,000 times, the thickness was measured, and the number was averaged to obtain the thickness. The aspect ratio was calculated and evaluated by dividing the length of the obtained long side by the thickness.

(4) Evaluation of BET specific surface area The BET specific surface area of flaky silver powder or spherical silver powder is evaluated by measuring 1 g of a sample using a monosorb (manufactured by Quanta Chrome) by a BET one-point method by nitrogen adsorption. did. In the measurement of the BET specific surface area, the deaeration conditions before the measurement were 10 minutes at 60 ° C.

(5) Evaluation of tap density The tap density of the flaky silver powder or the spherical silver powder was measured using a tap density measuring device (Casa specific gravity measuring device SS-DA-2 manufactured by Shibayama Scientific Instruments Co., Ltd.) The sample was weighed and placed in a 20 ml test tube, tapped 1,000 times with a drop of 20 mm, and the tap density was calculated by the following formula and evaluated.

Tap density = sample mass (15 g) / sample volume after tapping (cm ³ )
(6) Evaluation of sodium ion amount The sodium ion amount of flaky silver powder or spherical silver powder was evaluated by measuring 1 g of sample in nitric acid, adding pure water and diluting, and then measuring by atomic absorption method.

(7) Evaluation of degree of aggregation D50 / DSEM The degree of aggregation 50D / DSEM of the spherical silver powder is the average particle diameter D50 obtained by the laser diffraction method, as determined by a scanning electron microscope image (SEM, JSM-5500 manufactured by JEOL Ltd.). The average particle size of primary particles obtained from the image observation was calculated by dividing by DSEM and evaluated.

[Measurement of paste viscosity]
The paste viscosity of the conductive paste composition was measured using a DV-III viscometer manufactured by Brookfield. CP-52 is used as the cone for measurement, and the paste viscosity (η1 rpm) at 1 rpm rotation (shear rate 2 s-1) and the paste viscosity (η5 rpm) at 5 rpm rotation (shear rate 10 s-1) are measured. In addition, a TI value (η1 rpm / η5 rpm) obtained by dividing the former by the latter was calculated.

[Production method and evaluation method of characteristic evaluation sample]
Using the conductive paste compositions of Examples and Comparative Examples, samples for characteristic evaluation were produced as follows.

(1) Sample for contact resistance evaluation As a sample base material, a glass substrate with an ITO film (manufactured by Geomat Co., Ltd., surface resistance 6.6Ω / sq) was used. Then, as shown in FIG. 1, two strip-shaped conductor patterns 11 of 2 mm × 20 mm are formed in parallel on the surface of the glass substrate 21 using the conductive paste composition of the example or the comparative example. Screen printing was performed at intervals of 2 mm. For screen printing, a screen printer MT-320 manufactured by Micro Tech Co., Ltd. was used. Then, the glass substrate 21 was heated for 60 minutes in a 180 degreeC hot air dryer, and the conductor pattern 11 (conductive paste composition) was hardened. This produced the sample for contact resistance evaluation.

(2) Sample for evaluating specific resistance and solder wettability An alumina substrate was used as a sample base material. As shown in FIG. 2, the conductive paste composition of the example or comparative example is used on the surface of the alumina substrate, and terminals 12a and 12b are provided at both ends, and the wiring portion 12c is zigzag-shaped. The conductor pattern 12 and a 2 mm × 2 mm square conductor pattern (square pattern) (not shown) were screen-printed. Thereafter, the alumina substrate was heated in a hot air dryer at 180 ° C. for 60 minutes to cure the conductor pattern 12 (conductive paste composition). This produced a sample for evaluation of specific resistance and solder wettability.

(3) Evaluation of contact resistance About the contact resistance evaluation sample of each example or comparative example, the electrical resistance between each one end of the conductor patterns 11 and 11 was measured with a digital multimeter (R6551 manufactured by Advantest Corporation), Contact resistance was evaluated using the obtained resistance value.

  The evaluation standard for contact resistance was evaluated from a comparison between Comparative Example 1 and the examples and other comparative examples. That is, the contact resistance was normalized by dividing the resistance value measured in each Example or each Comparative Example by the resistance value measured in Comparative Example 1. In the following Examples and Comparative Examples, it was evaluated that the contact resistance was sufficiently small if the contact resistance was 1.00 or less, and it was evaluated that it was more preferable if the contact resistance was 0.90 or less.

(4) Evaluation of specific resistance For the specific resistance and solder wettability evaluation samples of each example or comparative example, the film thickness of the conductor pattern 12 was measured with a surface roughness meter (Surfcom 480A manufactured by Tokyo Seimitsu Co., Ltd.), and the electric resistance was measured. Measurement was performed with a digital multimeter (R6551 manufactured by Advantest Corporation), and the specific resistance was calculated and evaluated based on the film thickness, electrical resistance, and aspect ratio of the wiring pattern.

  As for the evaluation standard of the specific resistance, an upper limit value of the specific resistance was set, and the evaluation was made based on whether or not the specific resistance was lower. If the specific resistance of the wiring (electrode) is high, it is necessary to increase the film thickness in order to obtain the same level of wiring resistance, so that a large amount of the conductive paste composition to be used is also required. Therefore, it is preferable that the specific resistance of the electrode and wiring is as low as possible. In the following examples and comparative examples, the specific resistance of the wiring was preferably 10 μΩ · cm or less, more preferably 9 μΩ · cm or less, and more preferably 8 μΩ · cm or less.

(5) Evaluation of solder wettability After applying flux (XA-100 manufactured by Tamura Chemical Research Co., Ltd.) to five square patterns for the specific resistance and solder wettability evaluation samples of each example or comparative example, 230 ° C. Solder dipping was performed for 2 seconds in the solder bath set to. The solder wettability of the square pattern after dipping was visually confirmed, and the solder wettability was evaluated by calculating by dividing the area where the solder was raised by the area of the square pattern.

  With respect to the evaluation criteria for solder wettability, if the solder wettability is less than 80%, soldering may be difficult. Therefore, the solder wettability is preferably a numerical value higher than this. In the following examples and comparative examples, the solder wettability was preferably 80% or more, more preferably 90% or more, and even more preferably 100%.

(6) Evaluation of conductor pattern formation A comb-like conductor pattern having a line width of 100 μm is printed on an alumina substrate using the conductive paste composition of each example or comparative example as shown in FIG. The pattern was observed with a stereomicroscope. At this time, a case where none of the wiring drooling, wiring bleeding, and wiring blur was evaluated as “good”, and a case where at least one of wiring dripping, wiring bleeding, and wiring blur was recognized as “x”.

(Example 1)
Using the specific conductive powder shown in Table 1, the specific thermosetting component shown in Table 2, and the specific curing agent and solvent described in the margin of Table 3, these components are shown in Table 3. The conductive paste composition of Example 1 was manufactured (prepared) by blending with the compositions shown (all parts by mass) and kneading with a three-roll mill to form a paste.

  While measuring the paste viscosity of the obtained conductive paste composition, the contact resistance evaluation sample and the specific resistance and solder wettability evaluation sample described above were prepared, and the contact resistance between the conductor patterns 11 and 11, the conductor pattern The specific resistance of 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. The results are shown in Table 3.

(Examples 2 to 4)
As shown in Table 3, the epoxy resin B2 (Example 2), B3 (Example 3), or B4 (Example 4) (see Table 2 for all epoxy resins) is used as the B component, and the formulation of the solvent Except having adjusted the quantity, it carried out similarly to the said Example 1, and manufactured the electrically conductive paste composition of Examples 2-4. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 3.

(Example 5)
As shown in Table 3, spherical silver powder 2 (see Table 1) is used as the spherical powder in the conductive powder in the blending amount shown in Table 3, and the A component epoxy resin A2 (see Table 2) and B component epoxy are used. A conductive paste composition of Example 5 was produced in the same manner as in Example 1 except that the amounts of Resin B1 (see Table 2), blocked polyisocyanate compound of component C, curing agent 1 and solvent were adjusted. did. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 3.

(Example 6)
As shown in Table 3, the epoxy resin B2 (see Table 2) is used as the B component in the amount shown in Table 3, and the spherical silver powder 2 (see Table 1), the A component epoxy resin A2 (see Table 2), A conductive paste composition of Example 6 was produced in the same manner as in Example 5 except that the blending amounts of the blocked polyisocyanate compound of component C, the curing agent 1 and the solvent were adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 3.

(Example 7)
As shown in Table 4, while using spherical silver powder 2 (see Table 1) as the spherical powder in the conductive powder in the amount of Table 4, and using the epoxy resin A1 (see Table 2) as the A component, A conductive paste composition of Example 7 was produced in the same manner as in Example 1 except that the blending amount of the solvent was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 4.

(Examples 8 to 12)
As shown in Table 4, while using epoxy resin A3 (Examples 8 and 9), A4 (Example 10), A5 (Example 11), or A6 (Example 12) as the A component, 11 and 12, B2 was used instead of epoxy resin B1 (see Table 2 for all epoxy resins) to adjust the blending amount of the solvent, and Examples 11 and 12 were flaked as shown in Table 4. Except having changed the compounding quantity of silver powder and spherical silver powder 2, it carried out similarly to the said Example 7, and manufactured the electrically conductive paste composition of Examples 8-12. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 4.

(Example 13)
As shown in Table 5, Example 1 was used except that the curing agent 2 was used in the blending amounts shown in Table 5 and the blending amounts of the A component epoxy resin A2, the B component epoxy resin B1, and the solvent were adjusted. In the same manner as described above, the conductive paste composition of Example 13 was produced. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 5.

(Example 14)
As shown in Table 5, while the curing agent 1 was used in the amount shown in Table 5, the examples except that the amount of the component A epoxy resin A2 and the amount of the component B epoxy resin B1 were adjusted to be reversed were used. In the same manner as in Example 13, the conductive paste composition of Example 14 was produced. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 5.

(Examples 15 to 17)
As shown in Table 5, the epoxy resin A2 (see Table 2) is used as the A component, the epoxy resin B2 is used as the B component, and the blending amount of the blocked polyisocyanate compound of the C component is adjusted to be increased. Further, conductive paste compositions of Examples 15 to 17 were produced in the same manner as in Example 7 except that the blending amount of the solvent was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 5.

(Comparative Example 1)
As shown in Table 5, only the epoxy resin A2 of component A was used as the thermosetting component in the blending amounts shown in Table 5, the B component and the C component were not used, and the blending amounts of the curing agent 1 and the solvent were adjusted. A conductive paste composition of Comparative Example 1 was produced in the same manner as in Example 7 except for the above. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 5.

(Comparative Example 2)
As shown in Table 6, the epoxy resin A2 of component A and the blocked polyisocyanate compound of component C are used as thermosetting components in the amounts shown in Table 6, and the component B is not used. A conductive paste composition of Comparative Example 1 was produced in the same manner as in Example 7 except that the amount was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 6.

(Comparative Example 3)
As shown in Table 6, instead of using the B component as the thermosetting component, “other thermosetting component” (see Table 2), which is an epoxy resin having no cyclic structure, is used, and the blending of the solvent A conductive paste composition of Comparative Example 3 was produced in the same manner as in Example 1 except that the amount was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 6.

(Comparative Example 4)
As shown in Table 6, the total amount of the flaky silver powder and the spherical silver powder 2 used in combination as the conductive powder is 89 parts by mass, the epoxy resins A2 and B2, the blocked polyisocyanate compound of component C, the curing agent 1, In addition, a conductive paste composition of Comparative Example 4 was produced in the same manner as in Example 15 except that the blending amount of the solvent was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 6.

(Comparative Examples 5 and 6)
As shown in Table 6, Example 8 except that only the flaky silver powder (Comparative Example 5) or only the spherical silver powder 2 (Comparative Example 6) was used as the conductive powder and the blending amount of the curing agent 1 was adjusted. In the same manner, conductive paste compositions of Comparative Examples 5 and 6 were produced. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 6.

(Comparative Example 7)
As shown in Table 6, the epoxy resin B4 (see Table 2) is used as the B component, the blocked polyisocyanate compound of the C component is not used, and the epoxy resins A2 and B4, the curing agent 1, and the solvent are blended. A conductive paste composition of Comparative Example 7 was produced in the same manner as Example 15 except that the amount was adjusted. While measuring the paste viscosity of the obtained conductive paste composition, as described above, the contact resistance of the conductor pattern 11, the specific resistance of the conductor pattern 12, the solder wettability of the square pattern, and the formation of the conductor pattern 13 were evaluated. . The results are shown in Table 6.

[Characteristic evaluation results]
Each of the conductive paste compositions of Examples 1 to 17 can achieve good contact resistance, specific resistance, and solder wettability.

  On the other hand, since the conductive paste composition of Comparative Example 1 contains only the A component as the thermosetting component, the contact resistance cannot be reduced and the specific resistance cannot be sufficiently reduced. Moreover, although the conductive paste composition of Comparative Example 2 includes the A component and the C component as thermosetting components but does not include the B component, the contact resistance is slightly improved, but the specific resistance is sufficiently low. Can not do it.

  Moreover, since the conductive paste composition of Comparative Example 3 includes an epoxy resin (other thermosetting component) having no cyclic structure instead of the B component, the specific resistance can be lowered, but the contact resistance is reduced. And the conductor pattern cannot be formed satisfactorily. Further, since the conductive paste composition of Comparative Example 7 does not use the C component, the paste viscosity is low, the solder wettability is poor, and the conductor pattern cannot be formed satisfactorily.

  Moreover, from the result of Examples 1-17 and Comparative Examples 1-7, in the electrically conductive paste composition which concerns on this invention, as a compounding ratio of a thermosetting component, A component + B component: C component = 30: 70-90 : 10, and B component: A component + C component = 10: 90 to 70:30.

  Moreover, in Examples 1-4, Examples 7-15, and Comparative Examples 1-3, the conductive powder in solid content is 93 mass%, and in Example 5, the conductive powder in solid content is 94 mass%. In Example 6, the conductive powder in the solid content was 95% by mass, in Comparative Example 4, the conductive powder in the solid content was 89% by mass, and the contact resistance of Comparative Example 4 was the highest. Obviously, in the conductive paste composition according to the present invention, it is understood that the conductive powder in the solid content may be in the range of 90 to 98% by mass.

  Moreover, in Example 11, it is flaky silver powder: spherical silver powder = 60: 40 by mass ratio, and in Examples 1-10, Examples 13-15, and Comparative Examples 1-4 and 7, flaky silver powder: Spherical silver powder = 50: 50, in Example 12, flaky silver powder: spherical silver powder = 40: 60, whereas in Comparative Example 5, only flaky silver powder, in Comparative Example 6, spherical silver powder In Comparative Example 5, the solder wettability is poor, and in Comparative Example 6, the specific resistance is the highest. As is apparent from the conductive paste composition according to the present invention, the flaky powder is used as the conductive powder. A spherical powder may be used in combination, and at this time, it is preferable that the flaky powder: spherical powder = 20: 80 to 80:20.

  In addition, as is clear from the results of paste viscosities of Examples 1 to 15 and Comparative Examples 1 to 7, particularly η1 rpm viscosity, the conductive paste composition according to the present invention has a viscosity of 200 to 500 Pa · s at 25 ° C. It can be seen that it may be within the range of.

  It should be noted that the present invention is not limited to the description of the above-described embodiment, and various modifications are possible within the scope shown in the scope of the claims, and are disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the technical means are also included in the technical scope of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used in the field of manufacturing various electronic devices and electronic components, and in particular, collecting electrodes for solar cells, external electrodes for chip-type electronic components, RFID, electromagnetic wave shields, vibrator adhesives, membrane switches Alternatively, it can be suitably used in fields where it is required to form higher-definition electrodes and wiring such as electrodes and wiring of parts used for electroluminescence and the like.

DESCRIPTION OF SYMBOLS 11 Conductor pattern 12 Conductor pattern 12a Terminal 12b Terminal 12c Wiring part 13 Conductor pattern 21 Glass substrate with ITO film

Claims (10)

Containing a conductive powder, a thermosetting component, a curing agent, and a solvent;
As the conductive powder, flaky powder and spherical powder are used,
The thermosetting component is
Component A: an epoxy resin having a cyclic structure, having an epoxy equivalent of 160 to 400 and a viscosity at 25 ° C. of 3,000 mPa · s to 55,000 mPa · s;
Component B: an epoxy resin having a cyclic structure having an epoxy equivalent of 140 or more and 300 or less and a viscosity at 25 ° C. of 30 mPa · s or more and less than 3,000 mPa · s;
Component C: Consists of three components with a blocked polyisocyanate compound,
These A to C components are in a mass ratio, and the total amount of the A component and the B component and the amount of the C component are in the range of 30:70 to 90:10, and the amount of the B component and the amount of the A component and the C component The total amount is in the range of 10:90 to 70:30,
The ratio of the conductive powder in the solid content is in the range of 90 to 98% by mass,
Furthermore, the viscosity at 25 ° C. is in the range of 200 to 500 Pa · s,
Heat curable conductive paste composition. As the component A, at least one epoxy resin selected from the group consisting of bisphenol A type, bisphenol E type, bisphenol F type, phenol novolac type, chelate modified type, urethane modified type, and rubber modified type is used. Characterized by
The thermosetting conductive paste composition according to claim 1. As the component B, at least one epoxy resin selected from the group consisting of cyclohexanedimethanol type, dicyclopentadienedimethanol type, propylene oxide-added bisphenol A type, and chelate-modified type is used,
The heat-curable conductive paste composition according to claim 1 or 2. As the component C, a blocked polyisocyanate compound containing a polymethylene polyphenyl polyisocyanate having three or more nuclei is used,
The heat-curable conductive paste composition according to any one of claims 1 to 3. The flaky powder and the spherical powder are blended so as to be in a range of 20:80 to 80:20 by mass ratio,
The heat-curable conductive paste composition according to any one of claims 1 to 4. As the conductive powder, at least one selected from the group consisting of silver powder, copper powder, silver-coated copper powder, silver-coated nickel powder, silver-coated aluminum powder, and silver-coated glass powder is used,
The heat-curable conductive paste composition according to any one of claims 1 to 5. As the conductive powder, a sodium ion amount of less than 200 ppm is used,
The thermosetting conductive paste composition according to any one of claims 1 to 6. As the curing agent, acid anhydride, imidazole, a tertiary amine emissions or, wherein the Lewis acid or a compound containing boron fluoride is used,
The thermosetting conductive paste composition according to any one of claims 1 to 7. It is characterized in that it is used for forming an electrode or an electric wiring on the base material by heating and curing the conductor pattern printed on the base material,
The thermosetting conductive paste composition according to any one of claims 1 to 8. The electrode is a collecting electrode of a solar cell,
The thermosetting conductive paste composition according to claim 9.

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